Scavenger Receptors: Structure, Function and Diversity

Abstract

Abstract Scavenger receptors (SRs) form an increasingly important group of cell surface receptors that bind and internalise a variety of ligands. These membrane‐bound receptors were initially classified within this group on the basis of their ability to bind to modified low‐density lipoprotein (LDL) particles and as of date, at least 17 members of this family, organised into eight families, have been identified in nematodes, arthropods and higher organisms. Members of the SR family play key roles in many pathological conditions including pattern recognition in immune responses, pathogen infection and in the development and progression of atherosclerosis. The uptake of modified lipid particles by SRs in macrophages can lead to the formation of foam cells. Perturbation in the levels of some SRs can enhance or reduce the risk of cardiovascular disease. In this review, we describe the well‐characterised members of this group of proteins and discuss the functional and biological roles of these proteins in animal health and disease. Key Concepts: SR family contains membrane bound and soluble proteins. SRs bind to a variety of ligands including lipoproteins, carbohydrates and proteoglycans. SRs seem to play an important role in innate immunity against bacteria, with the lack of certain SRs leading to fatal susceptibility to infection. The malarial parasite and viruses may also exploit SR function to infect cells. SRs expressed in macrophages and endothelial cells bind to modified LDL particles to initiate atherosclerosis. The binding of modified LDL to SRs result in signalling cascades inside the cells, which may result in apoptosis. Knockdown of specific SRs or overexpression can reduce atherosclerosis incidence. SRs may also be involved in tumour metastasis.